Heat pulse experiments in superfluid 3He

Thermal Conductivity of Superfluid $$^3$$He-B in a Tubular Channel Down to 0.1$$T_\mathrm{c}$$ at the $$^{4}$$He Crystallization Pressure

“…Then, as the temperature was lowered, the conductivity showed a local minimum at 0.85T c (2.5 relative units) followed by a local maximum at 0.75T c (3.5), below which a monotonically decreasing behavior was observed. Between 0.3T c and 0.6T c , our data indicated ∼ 60% lower overall conductivity than the value determined from earlier studies [1,9,6,7]. We also showed that our measured temperature data was computationally reproducible using the determined thermal conductivity, meaning that the computational model can be used to estimate the lowest temperatures reached by the adiabatic melting method, when the quartz oscillator had become insensitive.…”

“…Wellard et al [6] studied the conductivity of superfluid 3 He down to 0.3T c by observing a time delay of a heat pulse between two vibrating wires, that was converted to diffusive conductivity by Einzel [7] as normalized to the normal fluid conductivity.…”

“…important just below the superfluid transition temperature T c , as it requires the presence of the normal component, and thus decreases exponentially with temperature. Diffusive conductivity has been discussed in several theoretical publications [2,3,4,5], and it has been measured using a heat-pulse method [6,7]. However, measurements of the total combined thermal conductivity have been made only on a narrow temperature span near the T c [8,9] at a selection of pressures.…”